The present invention relates to pipeline air release vent valves and, in particular, it concerns a pipeline air release vent valve having an elastic rolling shutter that closes gradually to prevent air valve pressure surges.
As a consequence of filling a pipeline with liquid, such as water, the air in the pipeline is vented through air release vent valves. During this process the trapped air is compressed and vents through the air release vent valve at a progressively higher velocity air flow.
It is known that the sudden stoppage of water flow as a common air release vent valve closes may create a distractive pressure surge.
Staging the closing process of the air release vent valve prevents the potential for pressure surges. Such staging provides a higher capacity air venting during a first stage and a low capacity air venting during a second stage.
The air release vent valve closes completely when the liquid level reaches the air valve float assembly and seals the (Kinetic and Automatic orifices) of the air release vent valve.
However, the sudden closing of a common rigid anti surge first stage large disc, as is the current solution for first stage closing, still causes a sharp pressure rise and potential damage to the valve and seal.
There is therefore a need for an air release vent valve having an elastic rolling shutter that closes gradually to prevent air valve pressure surges.